Synthesis and characterization of s-fac-[Co(dien)2](4-np)3(4-npH)·2H2O containing symmetric, [4-np…H…4-np]− and unsymmetric, [4-np-H…4-np−] dimers of 4-nitrophenolate (4-np−)

Encapsulation of halocadmate anion via hydrogen bonding: synthesis and characterization of bis(diethylenetriamine)cobalt(III) complex containing hexabromocadmate anion

“…The infrared spectrum (see Fig S1 ) of [Co(dien) 2 ] 3+ is much more distinctive and are useful for the identification of its isomers [ 34 ]. The most useful regions for their characterization are 950–800 cm −1 and 3000–2800 cm −1 .…”

“…In case of mer -isomer, the former region exhibits band of quartet (which is assigned for CH 2 -, NH 2 -, and NH-rocking modes and CN skeletal vibrations) and other two isomers ( s- and u-fac ) exhibit either fewer peaks or broad absorptions. In the latter region (for CH 2 stretching vibrations), very weak absorption band was reported for fac - isomers but strong for mer [ 34 ]. The CH 2 stretching vibrations have lower intensities as compared to the NH 2 stretching modes and are hardly recognizable for fac- isomers.…”

“…From the interpretation of IR spectrum it is concluded that the complex contains mer - isomer. The IR band assignments of new complex was compared with already reported [Co(dien) 2 ]Cl 3 in the literature [ 34 ]. The NH 2 bending vibrations were observed at 1559 cm −1 for newly synthesized complex.…”

“…The NH 2 bending vibrations were observed at 1559 cm −1 for newly synthesized complex. However, for [Co(dien) 2 ]Cl 3 , the NH 2 bending vibrations appeared at 1572 cm −1 [ 24 , 34 ]. The average 13 cm −l lowering in this frequency may indicate the weakening of N-H bonds due to presence of strong H-bonding interactions between cation and halocadmate anion.…”

“…In 1 H NMR spectra of s-fac or mer- [Co(dien) 2 ] 3+ isomers, there is presence of only two nonequivalent methylene groups due to which only quartet (for CH 2 adjacent to NH 2 ) and quintet (for CH 2 adjacent to NH) were expected [ 34 ]. In case of u-fac isomer, complex splitting pattern would be expected because of four nonequivalent methylene groups.…”